Highly active and sintering-resistant heteroepitaxy of Au nanoparticles on ZnO nanowires for CO oxidation

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• 作者：Jiaxin Liu^a ; ^b ; Botao Qiao^b ; ^c ; ^{bqiao@dicp.ac.cn" class="auth_mail" title="E-mail the corresponding author} ; Yian Song^b ; Hailian Tang^c ; Yudong Huang^a ; ^{ydhuang.hit1@aliyun.com" class="auth_mail" title="E-mail the corresponding author} ; Jingyue(Jimmy) Liu^b ; ^{Jingyue.Liu@asu.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Gold ; ZnO ; Nanowires ; Epitaxy ; CO oxidation ; Sintering ; Stability
• 刊名：Journal of Energy Chemistry
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：25
• 期：3
• 页码：361-370
• 全文大小：4389 K

文摘

Gold was supported on commercial ZnO powders (P) and homemade ZnO nanowires (NWs) by a modified deposition–precipitation method. X-ray diffraction and transmission electron microscopy investigation indicated that the size of the Au nanoparticles (NPs) depended strongly on the calcination temperature. The Au NPs were highly dispersed (< 5 nm) on both supports with calcination temperatures < 400 °C. However, after calcination at 600 °C the Au NPs aggregated much more severely on ZnO P than on ZnO NWs. Gold NPs epitaxially grew into the {10–10} facets of the ZnO NWs after calcination at temperatures > 400 °C. Such unique anchoring mechanism accounts for the much better experimentally observed sintering resistance. X-ray photoelectron spectra showed that Au existed as both metallic Au⁰ and Au^δ+ species in all the synthesized catalysts with or without calcination treatment; the ratios of Au^δ+/Au⁰, however, varied, depending on the treatment conditions. Catalytic tests showed that the activity for CO oxidation strongly depended on the size of the Au NPs. After calcination at 600 °C, the specific rate for CO oxidation at room temperature decreased about 30 times on Au/ZnO P but only about 4 times on Au/ZnO NW. Stability tests demonstrated that the Au/ZnO NW catalysts had better stability for CO oxidation.